Technical ReportPDF Available
Stored Grain
Department of Entomology
D. Baributsa1, I. Baoua2, T. Abdoulaye3, and L. Murdock1
1Department of Entomology, Purdue University, West Lafayette, IN, USA;
2Universite de Maradi, Maradi, Niger;
3International Institute of Tropical Agriculture, Nigeria
Post-harvest storage losses of grain to insects are at least
30% in Sub-Saharan Africa. There are many control methods but
most are minimally effective, expensive, not scalable, or present
health hazards.
The Purdue Improved Crop Storage (PICS) technology, a
triple layer bag composed of two polyethylene bags and one outer
woven polypropylene bag, minimizes insect storage losses. The
PICS bag works like other hermetic containers, by limiting the
supply of oxygen to insects living in stored grain. After PICS bags
are closed, insects in stored grain use up much of the oxygen left
inside the bag. When oxygen becomes too low, the insects cease
feeding, and stop growing and reproducing; this prevents serious
damage to the grain.
PICS bags were originally developed for cowpeas but later
shown to be effective against pests of several other stored crops
including maize, beans, sorghum, pigeon pea, peanuts, and rice.
A major effort to disseminate PICS bags in West and Central Africa
began in 2007.Work has since been expanded to East and Southern
Africa as well as Asia. By June 2015, more than 5 million bags had
been produced and sold by manufacturers and vendors to small-
holder farmers and other users. PICS training has reached millions
of farmers in more than 37,000 villages in Sub-Sahara Africa.
The PICS initiative aims to reduce post-harvest losses through
the use of hermetic storage methods; PICS bags being the main
driver. The instructions outlined here will serve as a guide for exten-
sion agents while implementing PICS activities. It describes steps in
using PICS bags, key recommendations, and questions frequently
asked by farmers.
Use of PICS bag - Procedure
The triple layer bag consists of two high density inner polyeth-
ylene plastic bags (inner liners) and a third outer sack (a woven
polypropylene bag). PICS bags should be handled carefully to
prolong their use and effectiveness.
Buy PICS bags from recognized
Make sure the bags being sold are
genuine, not counterfeits.
The bag should have the PICS lo-
gos displayed on both sides of the
woven bag.
The two inner liners should be thick
and fairly opaque.
Store only dry and clean grain that
contains no debris.
This will minimize damage to the
inner liner which could diminish ef-
Drying the grain adequately before
storage may help reduce the infes-
tation, maintain seed viability, and
minimize mold growth.
Separate the three
Check the integrity
of the two inner
liners for holes and
A PICS extension training.
Assess whether the bottom of both liners are well sealed.
Don’t use PICS bags with holes; they will be less effective.
A Guide on the Use of PICS Bags — E-265-W
It is the policy of the Purdue University Cooperative Extension Service that all persons have equal opportunity and access to its edu-
cational programs, services, activities, and facilities without regard to race, religion, color, sex, age, national origin or ancestry, marital
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October 2015
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Remember to:
Ø Store PICS bags away from sunlight or extreme heat.
Exposing bags to sunlight for long periods of time may damage
the woven bag and reduce its durability/usefulness.
Ø Store PICS bags on an elevated platform and away from walls
to facilitate inspection and minimize rodent attacks.
Ø Inspect PICS bags at least once a month.
Ø Keep PICS bag sealed at all times during grain storage. If grain
must be removed for home use or sale, ensure that excess air
is pressed out and the bag is resealed.
PICS technology is
Ø Easy to use, effective and no need to apply insecticides.
Ø Increases income and improves food security.
Ø Safely stores seed and grain.
Ø Grain stored in PICS bags may command a premium over
grain stored with chemicals.
Questions frequently asked by farmers.
ØShould we add insecticides to the PICS bag to improve
its effectiveness?
No, there is no need to add insecticides.
ØCan PICS bags be opened to remove some grain?
Yes, but the bag should be closed and resealed right away
to avoid reinfestation or resurgence of the insect
ØØCan seeds stored in PICS bags germinate?
Yes, but grain should be dried below 13% before storage
to maintain viability.
ØØCan PICS bags be reused?
Yes, three seasons on average. Avoiding holes in the
liners increases bag longevity
ØØCan I store several commodities in a PICS bag?
Yes, put each type of grain into a single small bag and put
all bags into a PICS bags. Seed and grain for home
consumption can be stored this way.
ØØWhy are PICS bags not available in smaller size?
Larger PICS bags (100 or 50 kg) can store smaller
quantities of grain (e.g. 20 kg). In addition, the storage cost
per kg is lower with larger bags, saving money.
ØØCan I store grain in PICS bag for one year or more?
Yes, grain can be stored in PICS bags for a year or more.
There are reports of grain being stored in PICS bags for
2 years or more.
Harvest time
Storage after 4 to 6 months
Woven bags
PICS sacks
Pour a small amount of grain into the
rst liner to allow it to be more easily
inserted into the second liner; then
put both liners into the woven sac.
Fold the lips of the three bags
together - from inside out.
Fill the inner bag with grain
while shaking gently to
eliminate pockets of air.
Make sure no grain gets
between the liners.
Ensure a lip remains at the top
for tying. Pack the grain tightly
to remove air.
Step 1: Gently twist
the lip of the most
inner liner, fold it over
and tie.
Benets of using PICS Technology
Step 2: Tuck the
knot from the rst
liner inside and re-
peat for the
second liner.
Step 3: Finally, tie
the woven bag. Be
sure to fold and tie
each bag
... All the maize was thoroughly mixed to ensure homogeneity before filling the bags. All bags were closed using strings as described in an extension training guide [33]. Each treatment was replicated four times. ...
... This is due to the training provided to farmers on proper handling of hermetic bags during storage. Farmers are advised not to store hermetic bags together with PP woven or jute bags that contain highly infested grain to minimize insect damage on the liners of hermetic bags from outside [27,33]. ...
... The second liner of the PICS™ bags provides extra protection in case of insect damage, given that most abrasions are limited to the inner most liner. To minimize damage on liners of hermetic bags, farmers are advised to store clean grain (right after harvest and drying) when the insect infestation is very low [33]. Other minor damages to liners such as small holes can be repaired with adhesive tape to increase the longevity of these hermetic bags. ...
Full-text available
Several postharvest technologies are currently being commercialized to help smallholder farmers in sub-Saharan Africa reduce grain storage losses. We carried out a study in Northern Benin to compare the effectiveness of five technologies being sold to protect stored grain. Maize that had been naturally infested by insects was stored in four hermetic storage technologies (SuperGrainbag™, AgroZ® bag, EVAL™, and Purdue Improved Crop Storage-PICS™ bags), an insecticide impregnated bag (ZeroFly®), and a regular polypropylene (PP) woven bag as control. Oxygen levels in hermetic bags fluctuated between 0.5 ± 0.0 (v/v) and 1.0 ± 0.3 (v/v) percent during the seven months of storage. No weight loss or insect damage was observed in grain stored in any of the hermetic storage bags after seven months. However, grain stored in ZeroFly® and PP woven bags had weight losses of 6.3% and 10.3%, respectively. These results will help farmers and development agencies when making decisions to use and/or promote storage technologies to reduce postharvest grain losses.
... In all, 36 bags (i.e., 12 PICS, 12 PP, and 12 jute) were used for the experiment. Before loading shea nuts into the hermetic bags, the two inner liners of each bag were checked for integrity by filling them with air to form a pouch before compressing them with both hands; any bag that leaked was discarded (Baributsa et al., 2015). The 36 bags of shea nuts were placed on pallets in the warehouse, as shown in Fig. 1. ...
... Grain used to grind the flour was not treated with any insecticides. Each layer of the PICS bag was tied separately, following the standard procedure [19]. Polypropylene bags were tied using a rope as well. ...
Full-text available
On-farm preservation of wheat flour is a challenge due to insect pests and high relative humidity. This experiment was conducted to assess the effectiveness of hermetic bags in preserving wheat flour stored by women during the wintertime when relative humidity is high. Forty women (households) from two districts in Herat province, Afghanistan, stored their wheat flour for 6 months. Each woman stored 25 kg of wheat flour in a Purdue Improved Crop Storage (PICS) bag and a polypropylene (PP) woven bag. Moisture content, insect population, flour color, bread taste, and profitability of storage were assessed. Moisture content and insect population significantly increased in PP bags after six months of storage, while no changes were observed in PICS bags. There was a significant negative correlation between wheat flour color and moisture content (r = −70.7, p < 0.001) and insect population (r = −79.9, p < 0.001). Wheat flour stored in PICS bags for 6 months retained its color and produced better bread than that stored in PP bags. Storing wheat flour in PICS bags for six months showed a return on investments (ROI) of + 16.9% against −33% for the PP bag. Farm households and other wheat value chain actors can safely store wheat flour in hermetic bags for up to six months under high relative humidity conditions. This would help improve food security for millions of wheat consumers in developing countries.
... All replicated treatment bags were filled with 50 kg of the field pea grains (see section 2.1). The two inner polyethylene bags and one outer woven polypropylene bag of the PICS bag were properly tied by folding the lips of the three bags together from inside out to prevent grain spillage and to ensure they were sealed based on the guidelines described by Baributsa et al. (2015). All bags were placed on wooden planks. ...
Field pea is an important pulse crop that plays a key role in human and animal nutrition as well as for soil fertility in many cropping systems. In East Africa, the pea weevil, Bruchus pisorum L. (Coleoptera: Bruchidae), is one of the main biotic production constraints causing considerable loss both in the field and during storage. The storage loss level depends on the number of weevils remaining in the seed after harvest and on the storage facilities and practices of the farmers. To address the storage losses, we evaluated the effectiveness of hermetic triple-layer Purdue Improved Crop Storage (PICS) bags, on stored grain quality and control of pea weevil infestation in Ethiopia. The PICS bag and two currently used farmers’ storage practices: polypropylene bag (PP) and polyethylene bag with Actellic dust (PE) were compared. Each bag was filled with 50 kg of field peas, and stored for 5 months. Fewer live adult pea weevils and lower percent grain damage was recorded in PICS and PE bags compared to PP bags along the storage period. Field pea grains stored in PICS bags and PE bag also retained higher germination capacity as compared to those stored in a PP bag. The proximate composition differed significantly between storage treatments during the trial. Grain stored in PICS bag and PE bag with Actellic dust showed higher grain moisture, crude protein, and crude fat content, but less total carbohydrate and ash content as compared with grain stored in PP bag. We concluded that PICS bags can be used by smallholder field pea growers to maintain grain quality postharvest, remove the need to use pesticides on their stored peas, and reduce pea weevil damage.
... Au total, 2000 individus de P. truncatus nouvellement émergés et non sexés ont été utilisés. Les sacs à triple fond ainsi que les sacs ordinaires ont été fermés hermétiquement à l'aide d'un fil en caoutchouc suivant la méthode décrite parBARIBUTSA et al. (2015). Après l'infestation et le conditionnement, les sacs ont été entreposés sur des palettes et dans les conditions ambiantes du laboratoire durant une période de six mois. ...
Full-text available
Cette étude vise à comparer les performances de sacs à triple fond utilisés au Burkina Faso pour la conservation des grains de maïs. Quatre types de sacs à triple fond (PICS, ETONG, PAPSA, et FAO) et un sac en polypropylène (témoin) ont été évalués. Cette évaluation a consisté à conditionner dans chaque type de sacs, 25 kg de grains de maïs infestés artificiellement avec 100 individus adultes de P. truncatus durant six mois dans les conditions ambiantes de laboratoire. Pour chaque type de sacs, 4 répétitions sont constituées. Les résultats montrent qu’au terme de cette période, 92 à 98% des individus adultes de P. truncatus étaient morts dans les sacs à triple fond comparativement au témoin (en polypropylène). Dans les sacs à triple fond, le taux de perforation des grains (7 à 16%), le taux de pertes en poids (1 à 2%) et le poids des débris farineux (1 à 4%) occasionnées par les insectes ne diffèrent pas significativement entre eux mais sont inférieurs à ceux observés dans les sacs en polypropylène. Les perforations des sachets interne et externe par P. truncatus n’ont pas varié dans les sacs à triple fond. Comparé à la situation initiale, le taux de germination des grains de maïs a baisé significativement de 22 à 33% dans les sacs de type FAO, ETONG et PICS qui ne diffèrent pas entre eux et de 64% dans les sacs PAPSA et les sacs sacs en polypropylène qui ne diffèrent pas aussi entre eux.
... Detailed characteristics of the various bags used in this experiment including brand, composition, thickness, and suppliers are provided in a similar study evaluating the use of hermetic bags for maize storage in Benin [19]. Liners were checked for holes or tears by filling them with air and bags were closed using strings after filling them with cowpea [34]. Naturally-infested cowpea was thoroughly mixed before filling 50 kg in each of the 4 replicates of every treatment (hermetic bag type). ...
Full-text available
Cowpea stored on smallholders’ farms suffers serious losses to insect pests. A study conducted in Niger compared five postharvest technologies marketed in sub-Saharan Africa to protect stored grain. Naturally-infested cowpea stored for eight months showed adult Callosobruchus maculatus (F.) mortality of 97% to 100% in the hermetic bags (PICSTM, SuperGrainbagTM, AgroZ®, EVAL™, and ZeroFly® bags). There was no change in grain damage and weight loss of cowpea stored in hermetic bags. There was, however, a loss of up to 10 to 16% in germination when the grain was stored in hermetic bags. Results observed for grain stored in ZeroFly® bags impregnated with deltamethrin were substantial and similar to those in control woven bags. In both ZeroFly® and woven bags, (1) adult C. maculatus population augmented by 35.7% and 78.6%, (2) increased weight losses of 27.3% and 25.2%, and (3) reduced germination of 37.0% and 28.8%, respectively. After opening the bags, abrasions were noted on the liners of hermetic bags, potential damage that could limit their reuse if they only have a single liner. Smallholder farmers in the Sahel can safely store their cowpea in all the hermetic bags tested. However, further research is needed to mitigate insect damage on liners of hermetic bags to improve their performance and reusability.
... Bags on pallets were arranged to form two layers of nine bags. The procedures recommended by Purdue University PICS team for using PICS bags were followed (Baributsa et al., 2015). These procedures involved storing properly dried corn (MC of 13%), checking that inner liners were not punctured before use, checking the integrity of the outer liner, and ensuring that bags were properly sealed. ...
Stored product insect pests cause significant losses in maize in sub-Saharan Africa (SSA). Control of these pests with conventional insecticides is fraught with health and environmental risks. Globally, several reduced-risk methods have been deployed as alternatives to conventional insecticides. In this study, conducted in FebruaryeDecember 2016, efficacies of five treatments to control insects in bagged maize stored in Nigerian market storehouses were evaluated. Treatments included a botanical (Piper guineense), Bularafa diatomaceous earth (DE), permethrin powder (Rambo™), PICS (hermetic) bags and ZeroFly® bags. The study also had a negative control comprising untreated maize in polypropylene bags. Study locations were in three grain markets, namely Eleekara market in Oyo town and Arisekola market in Ibadan, Oyo State, South West Nigeria, and Ago market in Ilorin, Kwara State, North Central Nigeria. Except in the case of PICS bags, each storehouse had six 100-kg bags for each storage method or treatment; these bags were sampled monthly. For PICS, each storehouse had 18 bags (~80 kg each) and six were destructively sampled every 4 months. Psocids (total 3,614) and S. zeamais (total 1,255) were the most abundant types of insects found during the study. However, among all treatments, PICS bags were the most effective at mitigating population growth of all species of stored product insects encountered, and the number of psocids and S. zeamais found in PICS bags during the entire study were 0 and 8, respectively. The order of effectiveness of the treatments were PICS > Permethrin > ZeroFly > DE > Botanical > control. Data showed PICS, Permethrin, ZeroFly, and DE when used according to manufacturer's instructions or label are effective and can be incorporated in integrated pest management of stored-product insects in maize storehouses. More research is required to explore how P. guineense can be made more efficacious.
... The grain was divided into 6 batches of 25 kg and transferred into two types of 50 kg capacity bags: Treatment 1-control polypropylene (PP) bag which were standard woven bags of 25 mm thick; Treatment 2: PICS bag made of two liners fitted inside a woven bag. The PICS bags were closed tightly in accordance with the method described by Baributsa et al. (2010Baributsa et al. ( , 2013Baributsa et al. ( , 2015. All bags of both treatments were tightly sealed with a rubber cord. ...
Full-text available
The PICS bags, originally developed for cowpea storage, were evaluated for sorghum (Sorghum bicolor) preservation. Batches of 25 kg of sorghum grain were stored in 50 kg PICS or polypropylene (PP) bags under ambient conditions for 12 months and assessed for the presence of insect pests and their damage, seed viability and, oxygen and carbon dioxide variations. The grain was incubated for 35 days to assess whether any insects would emerge. After six months of storage, oxygen levels decreased in the PICS bags compared to polypropylene bags. After 12 months of storage, only two pests, Rhyzopertha dominica and Sitophilus zeamais were found in the PICS bags. However, in PP bags there were additional pests including Tribolium castaneum and Oryzeaphilus mercator and Xylocoris flavipes. Grain weight loss and damage caused by these insects in the PP bags were significantly higher compared to those stored in PICS bags. Germination rates of sorghum grains stored in PP bags decreased significantly while no changes were observed in grains stored in PICS bags when compared to the initial germination. After the incubation post storage period, there was a resurgence of R. dominica in sorghum grains from PICS bags but the population levels were significantly lower compared to polypropylene bags. PICS bags preserved the quality and viability of stored sorghum grains and protected it from key insect pests. The PICS technology is effective for long-term sorghum storage but the potential resurgence of insects in low-oxygen environment calls for further research.
Full-text available
Coffee quality is generally evaluated through cupping, a technique based on sensory perceptions. Trained cuppers assign scores to ten quality attributes on a scale of 1 to 10. Exposure of coffee to moisture and/or oxygen during storage and/or transportation can affect the sensory evaluation and reduce the price received by farmers. This paper has two objectives. First, it estimates the effect of sensory scores and water activity on coffee price and its price differential from the market price. Second, it explores coffee sensory scores sensitivity to storage duration and water activity under two methods of application of the Purdue Improved Crop Storage (PICS) bags - the standard three layers PICS bag (PICS-3L) and the two layers PICS bag (PICS-2L). Data were collected for ten months from an experiment conducted in Manizales, Colombia. Results suggest, on average, that an additional point in the score of flavor or body increases the price of coffee by at least 66 COP/kg (0.015 USD/kg). If coffee has an additional point in aftertaste or uniformity from what is expected from other coffees of the same origin, then its price differential is reduced by at least 8 COP/kg (0.002 USD/kg). Using a PICS-3L bag instead of a PICS-2L bag does not affect the coffee price or sensory scores, but it reduces the price differential by approximately 18 COP/kg (0.004 USD/kg). On the other hand, water activity reduces coffee price but not its price differential. Storage time affects coffee sensory scores in some attributes, which may impact the coffee bean price.
Full-text available
Maize (Zea mays) is an important staple food crop for consumption and income. However, weevils continue to endanger household food security. A study was carried out in Bahir Dar University, Ethiopia, in 2019/2020, to develop more accessible and effective hermetic storage systems. Purdue Improved Crop Storage System (PICS) is good, but it is neither accessible nor affordable in Ethiopia. Therefore, other materials were tested in a completely randomised design replicated three times. After 3 months, number of alive and dead weevils, number of seeds with holes/grain damage and weight loss were assessed and analyzed using one-way ANOVA. Malathion treated grains, PICS, polyethylene bags and jerry cans had low weevil infestation, more dead weevils and less grain damage. Mean number of weevils alive per sample varied from 0 on Malathion to 200 on woven polypropylene bags. PICS bags were effective but could be replaced by polyethylene bags and jerry cans.
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